Process for dyeing animal and other fibers having similar properties



Patented May 8, 1951 PROCESS FOR DYEING ANIMAL AND OTHER FIBERS HAVINGSIMILAR PROPERTIES Richard Casty, Allschwil, Switzerland, assignor toCiba Limited, Basel, Switzerland, 'a Swiss No Drawing. Application June16, 1947, Serial No. 755,012. In SWitzerlandJune 28, 1946 11 Claims.

According to this invention animal fibers and other fibers, which havedyeing properties similar to those of animal fibers, are dyed in anespecial- ;ly simple manner by bringing the fibers impregnated'with thedyestufi" solution into sudden contact with a heated acidic solution.

As animal fibers which can be dyed by the present process there comeinto consideration, for example, silk fibers and especially wool fibers.Fibers which have dyeing properties similar to those of animal fibersare, for example, the artificial fibers consisting mainly of casein andknown under the names Thiolan and Lanital. There also come intoconsideration artificial silk fibers and staple fibers of cellulose 01'cellulose derivatives which have been animalized by the addition ofsuitable substances, and also other fibers which have been animalized bya special treatment.

In the present process such fibers are first soaked or impregnated witha dyestuff solution. This treatment may be carried out in known mannerby immersing the fibers in question in a dyestufi solution, andadvantageously subsequently squeezing the fibers. For the purposes ofthe present process the period of this treatment need only be longenough to brin about a uniform impregnation of the fibrous material. Itis not necessary or advantageous to prolong the period of treatmentbeyond this point. When materials of normal absorptive capacity areused, for example, in the case of fabrics which have been desized andadvantageously also washed and dried, the impregnation is carried on fora very short time and may, for example, be carried out on a paddingmachine.

The concentration of the dyestuff solution must, of course, be so chosenthat the desired quantity of dyestufi' remains on the fiber after theefiect of the squeezing operation has been taken into account. In somecases this necessitates relatively high concentrations of dyestufi inthe impregnating baths, and in the case of some dyestufis this can only.be achieved in a medium which is substantially non-acidic, for example,one which is approximately neutral or alkaline, and is advantageously atmost weakly alkaline. The use of a non-acidic impregnating bathgenerally has the further advantage that absorption of the dyestufif inthe bath is avoided to a considerable extent.

In some cases the temperature of the impreghatin bath plays a subsidiarypart and may be chosen, for example, with regard to the properties ofsolubility of the dyestuff used, within wide limits, for instance,between 20 C. and 95 C. In a few cases, however, there are differencesin the yield of the dyeing, so that it is of advantage in the case ofany particular dyestuff and fibrous material to determine by experimentthe most favorable temperature for the impregnating bath. In many casesa temperature of about C. gives good results.

Some degree of swelling of the fibrous material, which can be favoured,for example, by increasing the temperature of the impregnating bath, andalso thorough penetration of the fibrous material, which can beassisted, for ex:- ample, by the addition of certain wetting agents,

have a favorable effect in many cases. It must,

however, be borne in mind that some wetting agents, for instance, thoseof the type of alkylnaphthalene sulfonic acids, retard or even preventfixation of the dyestufi.

-In the case of dyestufis of insuflicient solubility it may be ofassistance in most cases to add solution promoters such as urea,thiodiglycol or glycol monoethyl ether, to choose especially easilysoluble dyestufif salts, for example, lithium salts, to increase thetemperature of the dyestuif solution or to use a combination of suchexpedients. In some cases a good eiiect is obtained by adding to theimpregnating bath a thickening agent such as tragacanth mucilage or awatersoluble cellulose ether, especially cellulose glycollic" acidether, and advantageously only in quantities such that the bath is stillthinly liquid. For example, there may be used, per liter, 50-100 gramsof tragacanth mucilage of 6 per cent. strength or of a solution of 10per cent. strength of cellulose glycollic acid ether.

Other additions are of advantage in the case of certain dyestuffs. Thus,for example, the addition of formaldehyde-sulfoxylates is of advantagewith impregnating baths which contain sensitive ester salts ofleuco-compounds of vat dyestuffs.

In the present process practically all dyestuffs can be used whichpossess an affinity for animal fibers, for example, the usual aciddyestuffs, and also substantive (direct dyeing) dyestufis and especiallydyestuffs which require a special aftertreatment, for example, chromedyestuffs and ester salts of leuco-compounds of vat dyestuffs. In thecase of dyestuffs of all kinds requiring an after-treatment it is, ofcourse, necessary to associate with the present dyeing process anappropriate after-treatment.

The fibers impregnated in the above manner with a dyestuif solution arethen brought into sudden contact with a heated acidic solution. As theacidic solution there may be used an aqueous solution of sulfuric acidsuch as is customarily used in dyeing wool and having a content of about-30 grams, and advantageously about 1 gram, of sulfuric acid per literof liquor. Instead of sulfuric acid other acids may be used in manycases, for example, formic acid or oxalic acid, and with specialadvantage in the case of dyestuffs which are sensitive to mineral acids.It is often of advantage to use mixtures of different acids, forexample, mixtures of sulfuric acid and formic acid, as in the case ofsulfuric acid leucoesters of indigo. In many cases it appears to be ofadvantage to useacidic solutions which have a pH value corresponding tothe 0p timum speed of fixation of the fibers in question, provided theydo neither unfavorably influence the dyestuff, nor for instance, producea skittery dyeing by too rapid fixation. In this connection the desiredpH value may be attained by using an acid salt alone or by the joint useof such a salt in any desired manner, for example, by means of monobasicsalts of ortho-phosphoric acid. This is indicated, more especially, inthe case of dyestuffs which become fixed very rapidly, such as thesulfuric acid esters of many leuco-compounds of vat dyestuffs. It isoccasionally of advantage to buffer the acids used by means of their ownsalts, for example, sulfuric acid by means of its own salts, forexample, sulfuric acid by means of sodium sulfate. Quite generally, inorder to obtain the best results, the concentration and nature of theacidic solution and also of the buffer substances, when used, should bechosen according to the character and quantity of the dyestufi used. Theoptimum conditions for each case can be determined by preliminary tests.

An addition of anion-active or cation-active substances to the acidicbath is generally not desirable and may even be harmful. 0n the otherhand, some non-ionisable wetting agents may in certain cases have afavorable influence. As such wetting agents there may be mentioned, forexample, condensation products of alcohols of high molecular weight withethylene oxide, which as is known contain polyglycol ether residues.

In the process of the invention it is of advantage to use stronglyheated acidic solutions, that is to say, those which are heated at above80 C., for example, boiling solutions.

The period during which the fibers impregnated with the dyestuffsolution are treated in the heated acidic bath need generally be onlyvery short, for example, to minutes. In many cases a period of treatmentof 2-7 minutes sufilces. The duration of the treatment depends mainly onthe dyestuif and on the intensity of the dyeing.

The present process enables the dyeing of animal fibers, especiallywool, to be carried out in a continuous manner, since the impregnationof the fibers and also the operation of bringing the impregnated fibersinto contact with the acidic solution require only a short time. Thus,for example, the fibers in the form of a woven fabric, knitted fabric,yarn or combed material or other loose form may be passed through apadding machine, advantageously provided with squeezing rollers disposedbeneath the level of the liquid, and then passed directly, or after anintermediate travel through the air, in a roller vat or a similarapparatus through the acidic bath. Care must naturally be taken to keepthe pH value of the acidic bath constantly at the optimum ascertainedfor the particular dyeing operation by renewing the acid and, whennecessary, the bufier salt.

The impregnated goods may be dried before the acidic treatment. In somecases somewhat stronger dyeings are obtained in this manner.

The fact that the present process succeeds is surprising in manyrespects. It could not be expected that the fixation of the dyestuffwould be possible in so short a time. Moreover, extraordinary inequalityin the dyeing result was to have been feared, and finally it would havebeen supposed that relatively large, and in some cases incalculable anduncontrollable, quantities of the dyestuff would be washed into theacidic bath. The process need not necessarily be carried out in acontinuous manner. The fibrous material may be treated in anon-continuous manner, provided that the fibers which have been treatedin the first step of the process are given a shock treatment with aheated acidic solution.

After the acidic treatment, the goods dyed by the present process may beimmediately rinsed and finished in the usual manner, provided that thedyestuff used does not necessitate any special after-treatment.

When dyestuffs are used in the process which require a specialafter-treatment, the latter treatment may be carried out in the knownmanner immediately following the present dyeing process. However, it isof advantage in many cases to carry out such after-treatment in acorrespondingly shortened manner so that it can be incorporated in thecontinuous dyeing process. Thus, for example, chrome dyestuffs,principally those which are resistant to an excess of bichromate, andalso ester salts of leuco compounds of vat dyestuffs, may be developedby passing the goods, immediately after leaving the acidic bath, into achrcming bath which is advantageously relatively strongly heated. Thelatter bath may contain, for example, up to 30 rams, and advantageouslyabout 5 to 10 grams, of sulfuric acid per liter and also a suitablequantity of potassium bichromate or sodium bichromate, for example, 0.5to about 3 grams per liter. In certain cases the sulfuric acid may bereplaced by another acid, for example, formic acid. Sometimes itsuffices to use alkali bichromate baths containing no acid addition. Inthe case of after-chromable dyestuffs it is of advantage to use aboiling bath, while in the case of ester salts of leuco-compounds of vatdyestufis a temperature of -90 C. often gives better results. Underthese circumstances the chroming or oxidation is generally completeafter about 15-60 seconds.

The goods after-treated in this manner are then advantageously rinsed,and treated in a suitable bath which has a neutralizing action andsimultaneously dissolves the excess of chromium compounds out of thefibers. As a neutralizing bath any oath having an alkaline reaction maybe used, and which may contain as an alkali, for example, sodiumcarbonate, ammonia, borax, secondary or tertiary sodium phosphate oreven ammonium carbonate. When a relatively high temperature is used, forexample 80 C., a period of treatment of about 2 minutes sufiices in mostcases, so that injury to the wool is avoided by the short duration ofthe treatment, especially when weak alkalies such as secondary sodiumphosphate are used.

If the after-treatment above described has undesired results, forexample, over-oxidation of the dyestuff used or a residual dyeing of thewool due to the excess of chromium, it may be of advantage to impregnatethe fibers first with a chromate solution which is at most weakly acid,for example, a bichromate solution, and then to bring them into an aciddeveloping bath. For example, after leaving the acidic bath which servesto fix the dyestuif, the fibers may be powerfully squeezed, and thenpadded or slopped on a padding machine having a smaller squeezing effectwith a concentrated, advantageously somewhat thickened, bichromatesolution. By suitably adjusting the two squeezing efiects and theconcentration of the chromate solution it is possible to ensure thatonly the final necessary quantity, possibly increased by a certainmargin of safety, is supplied to the fibers. Another method of charginga travelling Web of the goods with chromium is to spray it with achromate solution in a finely atomized state. Furthermore, by immersionfor some time in a chromate solution, followed, for example, by asqueezing operation the goods may be charged with chromium. In thiscase, however, the quantity of bichromate taken up depends very closelyon the period of immersion, the concentration, the temperature and thepH value of the chroming bath.

The fibers thus charged with chromic salts and dyestuff may then beintroduced directly into an acid bath, which in the case of ester saltsof leuco compounds of vat dyestuffs may contain, for example, 2 to 50grams, and advantageously 5 to grams, of sulfuric acid per liter. It isfrequently of advantage to add to the bath a small quantity, forexample, 0.5 to 2 grams perliter, of ammonium thiocyanate. Othersubstances such as oxalic acid or sulfites may in some cases also yieldgood results. A temperature of about 99 C. is usually advantageous.

For the aftertreatment of chrome dyestuffs it is often of advantage towork with boiling but relatively Weakly acid baths, for example, formicacid or acetic acid baths. In such cases excess sulfuric acidoriginating from the boiling fixing bath may be neutralized by theaddition, for ex ample, of sodium formate or sodium acetate. An additionof ammonium thiocyanate is also frequently of advantage in this case.These additions of buffer salts and thiocyanates may also be made to thepreceding chrome-charging bath. It is then frequently unnecessary tomake additions to the hot after-treatment bath.

The duration of the treatment in the latter r is it advisable to apply acold alkaline aftertreatment with, for example, 1 gram of anhydroussodium carbonate per liter.

An alternative method of oxidizing dyeings of ester salts ofleuco-compounds of vat dyestuffs is to pass the goods at 85-90 C. forabout 15-30 seconds through a bath containing, per liter, for example:

50 grams of concentrated sulfuric acid 30 grams of sodium chlorate and0.3 gram of ammonium vanadate.

After the completion of the dyeing process including any necessaryafter-treatments, the goods may be rinsed and finished in the usualmanner.

In many cases it is of advantage to add to the rinsing and neutralizingbaths washing agents of natural or synthetic character, which may serveto remove precipitated dyestufi particles on the surface.

In order to complete the treatment the goods, which have been thus dyed,may again be rinsed in the usual manner with cold, for example, running,water.

For carrying out the present process the continuous-dyeing machinesknown in the cotton dyeing industry may be used, in which case thetroughs or vats should be made of acid-resistant material, for example,acid-resistant steel, in view of the acid character of the fixing bathand, as the case may be, of the after-treatment bath. Slubbing may betreated on a machine which is similar in construction to the knownback-washing machine, and loose Wool on a type of Leviathan washingmachine, and so on. The period of travel of the goods through thetreatment baths is advantageously at or over the minimum at which a, ifdesired, very small but constant concentration of the dyestufi in thefixing bath is adjusted and the desired reaction in any after-treatmentbath is completed.

The following examples illustrate the invention.

E rample 1 Dry wool piece goods of light quality are impregnated at C.on a padding'machine or an impregnating machine with a solutioncontaining, per liter,

40 grams of the dyestufi of the formula r O H 40 cc. of thiodiglycol and2 grams of the sodium salt of benzyl-u-heptadeoyl-benzimidazoledisulfonic acid.

The goods, after being impregnated and squeezed, are passed immediately,or after passage through the air, through a roller vat of acidresistantmaterial which contains a boiling solution of 5 grams of concentratedsulfuric acid per liter. The goods are passed through the roller vat inan extended condition. The duration of the passage is 3-4 minutes. Thegoods are then rinsed in warm water, advantageously with the addition,per liter of rinsing liquor, of 1 gram of the sodium salt of benzyl--heptadecyl-benzimidazole disulfonic acid or of a similar acidresistantwashing agent. The washing and rinsing may be carried out in acontinuous manner on a broad washing machine or a skein washing machine.The goods are then dried. A powerful red dyeing is obtained.

Example 2 Loose washed wool is immersed in a bath at a temperature of 80C., which contains, per liter,

60 grams of Cloth Fast Black B in the form of the concentrated powder(Colour Index No. 307) 60 cc. of thiodiglycol and 2 grams of the sodiumsalt of benZyl;i-hepta decyl-benzimidazole disulfonic acid,

until it is completely wetted. The wool is then freed from excess of thedyestuff solution by squeezing, centrifuging or suction, and passed inthe course of 8 minutes through a boiling bath containing per liter,

7 cc. of formic acid and 3 cc. of a solution of about 20 per cent.strength of the condensation product of about 20 molecular proportionsof ethylene oxide with 1 molecular proportion of an ordinary commercialmixture of octadecyl alcohol and cetyl alcohol.

The material is then treated in warm water, which may have an additionof an acid-resistant washing agent, rinsed in the cold, and dried. Ablack dyeing is obtained.

Example 3 Slubbing of wool is dyed in a manner similar to that describedin Example 1. In the housing of an impregnating padding machine isplaced a solution containing 8 grams of the dyestufi of the formula:

NH I! i SOQNB Ii I O NH- NH-C OCH;

and 2 grams of the sodium salt of benzyli-heptadecyl-benzirnidazoledisulfonic acid at a temperature of 80 C. The combed material is passedthrough the padding machine and then brought into a boiling bathcontaining 1 gram of concentrated sulfuric acid and 4 grams ofcrystalline sodium sulfate, per liter. The material is treated in thisbath at the boiling temperature for 5 minutes, and then rinsed in asubsequent bath with blood-warm which may contain, per liter, 1 grain ofthe sodium salt of benzyl- -heptadecyl-benzi- .midazole disulfonic acid.The material is then 8 thoroughly rinsed in cold running water anddried. A blue dyeing is obtained.

Example 4 The procedure is the same as that described in Example 1,except that the impregnating liquor is at a temperature of 70 C. andcontains, per liter,

30 grams of Grange II (Colour Index 151) and 2 grams of the sodium saltof benzyl- -hepta decyl-benzimidazole disulfonic acid.

The impregnated material is then passed in the course of 5 minutesthrough a boiling fixing bath which contains, per liter, 1 grain ofconcentrated sulfuric acid. The material is then rinsed as described inExample 1. A powerful orange dyeing is obtained.

Example 5 The procedure is the same as that described in Example 1,except that the impregnating liquor is at a temperature of C. andcontains, per liter,

40 grams of Acid Black HA in the form of the concentrated dyestuffpowder (Colour Index 246),

cc. of thiodiglycol and 2 grams of the sodium salt of benzyl-;iheptadecyl-benzimidazole disulfonic acid.

The subsequent boiling fixing bath, contains, per

liter,

1 gram of concentrated sulfuric acid 2 grams of crystalline sodiumsulfate and 3 cc. of the ethylene oxide condensation product mentionedin Example 2.

The period of the passage is 7 minutes. The material is then rinsed,advantageously with the addition of the sodium salt of benzyl--heptadecyl-benzimidazole disulfonic acid, and dried. A black dyeing isobtained.

Example 6 The procedure is the same as that described in Example 1,except that the impregnating bath, used at 80 0., contains per liter,

25 grams of Chlorantin Red 8BN in the form of the concentrated dyestuffpowder (Colour Index 436),

20 cc. of thiodiglycol and 2 grams of the sodium salt of benzy1-,u-heptadecyl-benzimidazole disulfonic acid.

The material is then passed in an extended condition through a boilingfixing bath which contains, per liter,

1 gram of concentrated sulfuric acid, and 1.5 cc. of the ethylene oxidecondensation prodnot mentioned in Example 2.

The period of passage is 7 minutes. The material is then rinsed,advantageously with the addition of an acid-resistant washing material,again rinsed in water, and dried. A powerful wine red dyeing isobtained.

Errample 7 Slubbing of wool is treated in the manner described inExample 3, except that the impreghating liquor, used at 80 0., contains,per liter,

40 grams of Direct Fast Yellow FF (Colour Index No. 814) and 2 grams ofthe sodium salt of benzyl- -heptadecyl-benzimidazole disulfonic acid.

The material is then passed through a boiling fixing bath, whichcontains, per liter, 1 gram of concentrated sulfuric acid, 16 grams ofcrystalline sodium sulfate and 1.5 cc. of the ethylene oxidecondensation product mentioned in Example 2. The period of passage is 6minutes. The material is then rinsed and dried as described in theforegoing examples. A yellow dyeing is obtained.

Eatample 8 Dry wool piece goods of light quality are impregnated on thepadding machine or on an impregnating machine at 80 C. with a solutioncontaining, per liter, 15 grams of the complex chromium compound of thedystuff obtained from diazotized 1-hdyroxy-2-aminobenzene 4 sulfamideand 1-(3-sulfamido) phenyl-3-methyl-5- pyrazolone, in the form of aconcentrated dyestuff powder, and 2 grams of the sodium salt of benzyl aheptadecyl-benzimidazole-disulfonic acid. The goods, after beingimpregnated and squeezed, are passed immediately, or after passagethrough the air, through a roller vat of acidresistant material whichcontains a boiling solution of 1 gram of concentrated sulfuric acid and2 cubic centimeters of the ethylene oxide condensation product mentionedin Example 2. The period of passage is 6 minutes. After this, the goodsare thoroughly rinsed with warm water, advantageously with the additionof an acidresistant washing agent, rinsed again in cold water, anddried. An orange dyeing is thus obtained.

Example 9 Dry piece goods of wool are impregnated on a padding machineor in an impregnating machine permitting of the introduction of thegoods with a reduced air content, with a solution at a temperature of 80C. containing, per liter,

12 grams of the dyestuif obtainable from 2:6- dichloro-benzaldehyde and2 molecular proportions of ortho-cresotinic acid followed by oxidation,as described in Example 1 of German Specification No. 199,943, and

2 grams of the sodium salt of benzyl- -heptadecyl-benzimidazoledisulfonic acid.

The goods are passed in an extended condition through a boiling fixingbath, which contains, per liter, 2 cc. of formic acid of 85 per cent.strength and 4 grams of sodium formate. The period of passage is 6minutes. The material is then squeezed and immediately passed,advantageously while still in the extended condition, into a boilingchroming bath. The latter bath contains, per liter, 2 grams of sulfuricacid and 1 gram of potassium bichromate or sodium bichromate. The periodof passage is 45 seconds. The goods are then rinsed in warm water. Inorder to remove the yellow coloration due to the chroming the goods arepassed into a bath at 80 C. which contains, per liter, 10 grams ofcrystalline disodium phosphate and 1 gram of the sodium salt of benzyl--heptadecyl-benzimidazole disulfonic acid. The period of passage is 2minutes. The goods are then thoroughly rinsed. A pure blue dyeing isobtained.

Example 10 Washed loose wool is immersed until completely wetted in abath at 80 C. which contains, per liter, 10 grams of the dyestuifobtainable from diazotized 4 chloro-2-amino-l-hydroxybenzene- 6-su1fonicacid and l-phenyl-3-methyl-5-pyrazolone. The wool is freed from excessof the dyestuff solution by squeezing, centrifuging or suction, and thenpassed in the course of 6 min utes through a boiling bath which containsper liter 1 gram of concentrated sulfuric acid and 2 grams ofcrystalline sodium sulfate. It is then squeezed, and sprayed with asolution which contains, per liter, 30 grams of potassium bichromate orsodium bichromate and 250 grams of crystalline sodium acetate. Theapparatus is so arranged that the quantity of the sprayed solution takenup by the loose wool amounts to 50 per cent. of the dry weight of thelatter. In this manner the wool is charged with 1.5 per cent. ofbichromate and a sufficient quantity of buffer salt to neutralize theexcess sulfuric acid. The wool I is then passed for '7 minutes through abath of boiling water. It is then rinsed in the warm and Example 11 Animpregnating bath is prepared, which contains, per liter,

25 grams of the dyestufi from diazotized 4-chloro-2-amino 1hydroxybenzene and 1 :8-dihydroxy-naphthalene-3 G-disulfonic acid,

20 cc. of thiodiglycol and in the cold, and dried. A red dyeing isobtained.

2 grams of the sodium salt of benzyl-a-heptadecyl-benzimidazoledisulfonic acid.

A wool fabric is treated on a padding machine in this bath at 0., andsqueezed until its content of moisture is 100 per cent. The fabric isthen treated for '7 minutes at the boiling temperature in a bath whichcontains, per liter, 2 grams of concentrated sulfuric acid and 2 cc. ofthe ethylene oxide condensation product mentioned in Example 2. Afterrigorous squeezing the material is padded with a thickened bichromatebath which contains per liter 26 grams of sodium bichromate and 100grams of a solution of 10 per cent. strength of cellulose glycol ether.The apparatus is so adjusted that the increase in weight of the wetgoods in the padding machine, as compared with the previous squeezingmachine, amounts to 80 per cent. on the dry weight of the goods. In thecase of different squeezing conditionsthe concentration of bichromate inthe padding bath must be proportionately changed. The material is thenpassed into a bath which contains, per liter, /2 cc. of formic acid ofper cent strength, 1 gram of sodium formate and 1 gram of ammoniumthiocyanate. The wool is treated in this bath for '7 minutes at theboiling temperature, and is then rinsed and finished in the usualmanner. A dark blue dyeing is obtained.

Ezcample 12 Loose wool is impregnated at 70 C. with a solution whichcontains, per liter,

25 grams of the sodium salt of the sulfuric acid leuco-ester of6:6-diethoXy-thioindigo,

25 grams of the sodium salt of the sulfuric acid leuco-ester of 4:4dimethyl 6:6 dichlorothioindigo,

50 cc. of thiodiglycol,

15 grams of sodium formaldehyde sulfoxylate and 2 grams of the sodiumsalt of benzyl- -heptadecyl-benzimidazole-disu1fonic acid.

The material is then passed in the course of '7 minutes through aboiling bath which contains per liter, 1 cc. of formic acid of 85 percent. strength, 4 grams of sodium formate and 3 cc. of the ethyleneoxide condensation product mentioned in Example 2. The wool is thenpassed and 1 gram of sodium bichromate.

Dry Wool muslin is impregnated on a threeroller padding machine or in amodern impregnating machine permitting of the introduction of the goodswith a reduced air content, with a solution at 75 C. which contains perliter,

8 grams of the sodium salt of the sulfuric acid leuco-ester of thedyestufi of the formula Q o Br 01 grams of sodium formaldehydesulfoxylate and 2 grams of the sodium salt of benzyl- -heptadecyl-ioenzimidazole disulfonic acid.

The goods are then passed immediately into a roller vatcompcsed ofacid-resistant material, which contains, an approximately boilingsolution of 10 grams of mono-ammonium phosphate and 1 cc. of theethylene oxide condensation product mentioned in Example 2, per liter.The period of treatment in this bath is 3 minutes.

The squeezing goods are then padded in the manner described in Example10 with a thickened solution containing per liter,

9 grams of potassium bichromate or sodium bichromate,

9 grams of ammonium thiocyanate and 100 grams of a solution of 10 percent strength of cellulose glycol ether.

The goods are then treated for 2 minutes at 90 C. in a bath containing10 grams of concentrated sulfuric acid per liter. The goods are thenrinsed in the Warm, if desired with the addition of an acid-resistantWashing agent, then neutralized in the cold with a solution containing 1gram of anhydrous sodium-carbonate per liter, and again rinsed, anddried. A grey dyeing is obtained.

Example '14 A Wool fabric is treated on the padding machine at 70 C. ina bath which contains per liter,

10 grams of the sodium salt of the sulfuric acid ester of the leucocompound of 4:7-dimethyl 6':6-dichloro-thioindigo 10 grams of sodiumformaldehyde sulfoxylate 100 grams of a solution of 10 per cent strengthof cellulose glycol ether and 2 grams of the sodim salt ofhenzyl-;i-heptadecylbenzimidazole disulfonic acid.

The goods are then treated for 5 minutes at the boiling temperature in abath containing per liter, grams of monoammonium phosphate and 1 cc. ofthe ethylene oxide condensation product described in Example 2. Thematerial is then padded in the manner described in Example 10 in a bathcontaining, per liter, 13 grams of so l2 dium bichromate and 100 gramsof a solution of '10 per cent strength of cellulose glycol ether, andthe goods are then passed into a bath which contains, per liter, 10grams of concentrated sulfuric acid and gram of ammonium thiocyanate. Inthe latter bath the goods are treated for 4 minutes at 90 C. The goodsare then rinsed in the warm, neutralized in the cold with a dilutesolution of sodium carbonate, and again rinsed, and dried. A fast pinkdyeing is obtained.

Example 15 Wool piece goods are treated in accordance with the proceduredescribed in Example 1. The impregnated liquor used at C. contains perliter;

160 grams of the sodium salt of the sulfuric acid leuco-ester of indigo20 grams of sodium formaldehyde sulfoxylate and 2 grams of the sodiumsalt of benzyl- -heptadecyl-benzimidazole disulfonic acid.

The succeeding fixing bath contains an approximately boiling solutioncontaining per liter, 1 gram of concentrated sulfuric acid, 1 cc. offormic acid of per cent. strength and 3 cc. of the ethylene oxidecondensation product mentioned in Example 2. The period of passage is 7minutes. The goods are then padded in the manner described in Example 11in a thickened solution which contains per liter, 35 grams of potassiumbichromate or sodium bichromate and 100 grams of a solution Of 10 percent. strength of cellulose glycol ether. The goods are then passed inthe course of 3 minutes through a bath at 80-90 C. which contains, perliter, 8 grams of concentrated sulfuric acid and 2 grams of ammoniumthiocyanate. The goods are then rinsed in warm water which contains 1gram of the sodium salt of benzyli-heptadecyl-benzimidazole disulfonicacid per liter. The goods are then neutralized in the cold with asolution containing 1 gram of anhydrous sodium carbonate per liter,rinsed, and dried. A powerful deep 'blue dyeing is obtained.

Example 16 Slubbing of Wool is treated in the manner described inExample 3, except that the impregnating liquor, is used at 60 C., andcontains, per liter,

30 grams of the sodium salt of the sulfuric acid leuco-ester ofdimethoxy-dibenzanthrone,

10 grams of sodium formaldehyde sulfoxylate and 2 grams of the sodiumsalt of benzyl- -heptadecyl-benzimidazole disulfonic acid.

The succeeding boiling fixing bath contains, per liter, 1 cc. of formicacid, 8 grams of sodium formats and 5 cc. of the ethylene oxidecondensation product mentioned in Example 2. The period of treatment is6 minutes. The combed material is then passed into the oxidizing bath.The latter which is used at C., contains per liter,

50 grams of concentrated sulfuric acid,

30 grams of sodium chlorate and 0.3 gram of ammonium vanadate.

The period of passage is 20 seconds. After being squeezed the goods arerinsed in the warm and then introduced into a cold neutralizing bathcontaining per liter, 2 grams of anhydrous sodium carbonate and, ifdesired 1 gram of the sodium salt of benzyl-,u-heptadecyl-benzimidazoledisulfonic acid. The goods are then thoroughly rinsed and dried. A greendyeing is obtained.

What I claim is:

1. A process for dyeing wool which comprises bringing wool impregnatedwith a solution of a dyestufi of the kind possessing affinity for W001due to the presence of acid groups in the dyestuff into sudden contactwith an aqueous acidic solution, heated to about its boiling point, theacidity of which corresponds to that of a solution containing not morethan 30 grams of H2804 in one liter of water, the said acidic solutionbeing free from oxidizing agents and free from reducing agents harmfulto the dyestufi, the whole dyeing operation being carried out underatmospheric pressure.

2. A process for dyeing wool which comprises bringing wool impregnatedwith a substantially non-acidic solution of a dyestuff of the kindpossessing afiinity for wool due to the presence of acid groups in thedyestufi into sudden contact with an aqueous acidic solution, heated toabout its boiling point, the acidity of which corresponds to that of asolution containing not more than 30 grams of H2804 in one liter ofwater, the said acidic solution being free from oxidizing agents andfree from reducing agents harmful to the dyestuff, the whole dyeingoperation being carried out under atmospheric pressure.

3. A process for dyeing wool which comprises bringing wool impregnatedwith a substantially non-acidic solution of an acid wool dyestufi intosudden contact with an aqueous acidic solution, heated to about itsboiling point, the acidity of which corresponds to that of a solutioncontaining not more than 30 grams of H2804 in one liter of water, thesaid acidic solution being free from oxidizing agents and free fromreducing agents harmful to the dyestuff, the whole dyeing operationbeing carried out under atmospheric pressure.

4. A process for dyeing wool which comprises bringing wool impregnatedwith a substantially non-acidic solution of a substantive dyestuffpossessing acid groups into sudden contact with an aqueous acidicsolution, heated to about its boiling point, the acidity of whichcorresponds to that of a solution containing not more than 30 grams ofH2804 in one liter of water, the said acidic solution being free fromoxidizing agents and free from reducing agents harmful to the dyestuff,the whole dyeing operation being carried out under atmospheric pressure.

5. A process for dyeing wool which comprises bringing wool impregnatedwith a substantially non-acidic solution of a sulfuric acid ester of aleuco vat dyestuff into sudden contact with an bringing wool impregnatedwith a N aqueous acidic solution, heated to about its boiling point, theacidity of which corresponds to that of a solution containing not morethan 30- grams of H2804 in one liter of water, the said acidic solutionbeing free from oxidizing and free from reducing agents harmful to thedyestuff, the whole dyeing operation being carried out under atmosphericpressure.

6. A process as claimed in claim 1, wherein the acidity of the aqueousacidic solution corresponds to that of a solution containing about 1gram of H2804 in one liter of water.

7. A process as claimed in claim 2, wherein the acidity of the aqueousacidic solution corresponds to that of a solution containing about 1gram of H2804 in one liter of water.

8. A process as claimed in claim 3, wherein the acidity of the aqueousacidic solution corresponds to that of a solution containing about 1gram of H2804 in one liter of water.

9. A process as claimed in claim 4, wherein the acidity of the aqueousacidic solution corresponds to that of a solution containing about 1gram of H2804 in one liter of water.

10. A process as claimed in claim 5, wherein the acidity of the aqueousacidic solution corresponds to that of a solution containing about 1gram of H2804 in one liter of water.

11. A process for dyeing wool which comprises substantially non-acidicsolution of an acid wool dyestuff capable of being after-chromed intosudden contact with an aqueous acidic solution, heated to about itsboiling point, the acidity of which corresponds to that of a solutioncontaining about 1 gram of H2804 in one liter of water, the said acidicsolution being free from oxidizing and free from reducing agents harmfulto the dyestuif, then charging the wool with the required amount of achromate solution and subjecting the wool to an acidic treatment foreffecting the chroming reaction, the whole dyeing operation beingcarried out under atmospheric pressure.

RICHARD CASTY.

REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS Number Name Date 1,575,958 Bader Mar. 9, 19261,850,551 Jones Mar. 22, 1932 2,095,600 Graenacher Oct. 1 1937 2,387,200Walter Oct. 16, 1945 OTHER REFERENCES Amer. Dye. Reporter for Jan. 10,1949, pp. P9, P26-P32.

1. A PROCESS FOR DEYING WOOL WHICH COMPRISES BRINGING WOOL IMPREGNATEDWITH A SOLUTION OF A DYESTUFF OF THE KINE POSSESSING AFFINITY FOR WOOLDUE TO THE PRESENCE OF ACID GROUPS IN THE DYESTUFF INTO SUDDEN CONTACTWITH AN AQUEOUS ACIDIC SOLUTION, HEATED TO ABOUT ITS BOILING POINT, THEACIDITY OF WHICH CORRESPONDS TO THAT OF A SOLUTION CONTAINING NOT MORETHAN 30 GRAMS OF H2SO4 IN ONE LITER OF WATER, THE SAID ACIDIC SOLUTIONBEING FREE FROM OXIDIZING AGENTS AND FREE FROM REDUCING AGENTS HARMFULTO THE DYESTUFF, THE WHOLE DYEING O-ERATION BEING CARRIED OUT UNDERATMOSPHERIC PRESSURE.